Yukov tissue characterization method and apparatus

ABSTRACT

A systems and methods for tissue characterization using ultrasound are disclosed. One embodiment is for a system with a novel YB-scan transducer. The YB transducer is comprised of a plurality of separate and independent piezo-elements. The system is configured to scan a tissue or organ using two different frequencies to produce 2D images and two-frequency attenuation data to characterize tissue types. Other embodiments are presented permitting conventional B-scan imaging combined with A-mode scanning for two-frequency tissue characterization.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of pending application Ser. No.16/504,276, filed on Jul. 7, 2019. Application Ser. No. 16/504,276 is aDivision of Ser. No. 15/732,780 filed 2017 Dec. 29 that was issued asU.S. Pat. No. 10,383,597 B2 on Aug. 20, 2019. Application Ser. No.15/732,780 was a Continuation-In-Part of application Ser. No. 14/998,914filed 2016 Mar. 4. This application claims benefit to the filing datesof application Ser. No. 16/504,276, application Ser. No. 15/732,780 andapplication Ser. No. 14/998,914. The contents of application Ser. Nos.16/504,276, 15/732,780 and 14/998,914 are, in their entirety,incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to systems and methods for non-invasivelydetermining the type of tissue matter or the state of tissue matter in aliving body. The present invention allows physicians and diagnosticiansto determine the presence of healthy or unhealthy tissue and todetermine a proper course of treatment.

Description of Related Art Including Information Disclosed Under 37 CFR1.97 and 1.98

The present invention relates to improvement of the quality of existingultrasound diagnostic examination by applying a combined transducerwhich can integrate a two-dimensional (YB-scan and B-scan) visualizationtechnique with an A-mode transducer of a Two-Frequency Attenuationtechnique to obtain high quality ultrasound diagnostic examinationincluding non-invasively determination the type of the issue matterunder ultrasound investigation.

For many years specialists in ultrasound diagnostic field trying todevelop an ultrasound diagnostic method and apparatus which can provideinformation to differentiate type of tissue through measuringattenuation data in a living body or by finding a pattern of the tissuetype images. There are many attempts to reach that goal by usingspectrum analyzes of reflected signals like U.S. Pat. No. 6,007,489 toYost et al., European Patent No. 11840135 to Hironaka and many othersthat could not come up with an objective and reliable method forclinical applications. Some specialists like European Patent No.PCT/IB2014/067105 to Schneider, European Pat. No. PCT/CA2014/2014/050480to Sadeghi, U.S. patent Ser. No. 14/096,960 to Anuja, European Pat. No.PCT/US2014/011631 to Chen and others tried to find a pattern in a tissueimages to differentiate the type of tissue. All attempts to find somepositive information to improve B-scan visualization examination todifferentiate type of tissue was not successful since the amplitudes ofreflected echo-signals depend not only on attenuation information frominside of the tissue structure but also on interference phenomena duringreflection from the reflected surface, the angle of incident of theultrasound pulses to reflected surface, its geometry and roughness.Attempts to find a system employing ultrasound methods for determinationthe nature of tissue within a living body is still continuing. One suchsystem is disclosed in U.S. Pat. No. 5,361,767 to Yukov. This systemdetermines a type of tissue by using methods and apparatuses for a“Two-Frequency Method” of tissue characterization which is based onapplying two different frequencies and by registering reflected signalsto calculate a differential attenuation coefficient of the tissuethrough formula I:

$\begin{matrix}{{{a\left( f_{2} \right)} - {a\left( f_{1} \right)}} = {\frac{\frac{A_{1}\left( f_{2} \right)}{A_{2}\left( f_{2} \right)} - \frac{A_{1}\left( f_{1} \right)}{A_{2}\left( f_{1} \right)}}{2\; I}{db}\text{/}{Cm}\text{/}{MHz}}} & (I)\end{matrix}$

where a(f₁) and a(f₂)—attenuation coefficient on frequencies f₁ and f₂accordingly; A₁ (f₁), A₂(f₁) and A₁(f₂), A₂(f₂) are amplitudes of thereflected signals from front and rare boundaries of a layer onfrequencies f₁ and f₂ accordingly; I—is a thickness of a layer.

Author describes requirements for the reflected signals to be processedthrough mathematical algorithm since as mentioned there is no directdependency between the amplitude of reflected signals and attenuationinformation. For that purpose, author suggests obtaining objectiveinformation related to attenuation data through analyses of the shape,width and registered time of reflected signals on applied two differentfrequencies. Chinese Patent No. CN1113631C to Korotkoff discloses atwo-frequency method and apparatus which is based on a developed“Two-Frequency Method” described in U.S. Pat. No. 5,361,767. Authorsuggests using a conventional B-scan transducer with subtraction of theamplitudes of reflected signals automatically on two differentfrequencies and displaying the results as a two-dimensional attenuationimage on the screen. As mentioned since there is no direct dependencybetween amplitudes of reflected signals and attenuation information theapparatus in Chinese Pat. No. CN1113631C for automatic two-dimensionalattenuation image display cannot obtain objective attenuationinformation and it will be impossible to apply in the clinicalenvironment as an objective diagnostic method. The U.S. Pat. No.1,249,164 to Ke Jian with a Title “Human Tissue Ultrasonic AttenuationImaging Technology” also applies a regular multi piezo elements B-scantransducer on two different frequencies and suggesting to applyseparately two different regular_B-scan transducers on differentfrequencies “duplex frequency and double probe” which cannot make itpossible to obtain objective attenuation information for the reasons ofthe ultrasound wave reflection properties as mentioned above. ThePatents to Kossoff (U.S. Pat. No. 3,881,164) where author suggesting toimprove focusing of A-mode transducer by using two transducers andColeman et al. (U.S. Pat. No. 4,932,414) where author using mechanicallymoving A-mode transducer to make a scanning two-dimensional images tofind out area of abnormality to apply radiation treatment are not belongto a two-frequency examination or attenuation measurement method andcannot be compared to Yukov Tissue Characterization Method. The PatentNo. US20140350403 to KHO et al is a totally different method whichapplies multiple transducers focused in one point to evaluate theattenuation in that organ and it cannot be compared to Yukov TissueCharacterization Method.

Very sharp and short excitation pulses of a B-scan imaging system leadto a very high resolution of the tissue structure images. However, inmany cases there is still not enough information to differentiate thetype of abnormalities in the patient's body. B-scan imaging system needsome extra information to resolve this problem. One type of neededinformation would account for different attenuation values according tothe type of tissue.

The U.S. Pat. No. 5,361,767 to Yukov suggests using the Two-FrequencyMethod as a Tissue Characterization Method together with a B-scan tissuestructure image information, which makes it easier to find a spot ofinterest for measurement of attenuation. This reference also suggestsusing the same B-scan transducer simultaneously, in sequence oralternately as a B-scan image visualization method and as a transducerfor a Two-Frequency Attenuation Method in order to calculate attenuationdata from a spot of interest for generating tissue characterizationinformation. Yukov did not mention that there are fundamentaldifferences between the requirements for B-scan transducers andTwo-Frequency Attenuation Method transducers. B-scan transducers requiredifferent types of excitation pulses which must be very sharp and shortto achieve high resolution of tissue structure images. In contrast, theexcitation pulse for a Two-Frequency Method transducer consist ofseveral sine-waves.

Another big difference is that a B-scan transducer requires multiplepiezo-elements but a Two-Frequency Method transducer requires only onepiezo-element (i.e., only one emitter-receiver source). Because of thesedifferences there are limitations for applying a regular B-scantransducer for both methods. It is impossible to apply without re-designand re-engineering existing B-scan transducers to integratetwo-dimensional visualization technique and A-mode transducer ofTwo-Frequency Attenuation Method technique as one combined transducer tohave a high-quality ultrasound diagnostic examination.

Applying B-scan image visualization combined with a Two-FrequencyAttenuation Method for tissue characterization can improve quality ofthe ultrasound diagnostic examinations and will make it possible todetermine types of the tissue non-invasively in a living entity.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to improve the quality ofcurrent diagnostic examination methods by providing a YB-scan imagingsystem that can perform 2-dimensional ultrasound visualization at twofrequencies with two-frequency attenuation analysis thereby allowingnon-invasive determination of the type of tissue under investigation.

It is also an object of the present invention to improve the quality ofcurrent diagnostic examination methods by providing a system having aversatile transducer, which may be comprised of a combination oftransducers, with the system further having components to permitgeneration of two-dimensional images, typically known as B-scan images,and with generation of two-frequency tissue characterization data, whichmay also be displayed graphically. According to the principles describedherein, two-dimensional ultrasound images are used to identify a spot ina region of interest which is characterized by analysis of thetwo-frequency attenuation data.

One embodiment integrates, through a novel transducer, simultaneousapplication of a two-dimensional B-scan image visualization method and atwo-frequency tissue characterization method where a B-scan image isused as a guiding image to be used with two-frequency tissuecharacterization data to overcome the aforementioned problems. B-scanimages produced with this novel YB-scan transducer are referred to asYB-scan images or YB-images.

It is a further object of the present invention to improve the qualityof ultrasound diagnostic examination with a system having a novelversatile transducer, fabricated from an existing B-scan transducercurrently available on the market, or fabricated de novo, which canreversibly permit a subset of piezo-elements in the transducer tooperate as an A-mode transducer. Additional system components wouldadapt conventional B-scan systems to perform both B-scan imaging andtwo-frequency A-mode tissue characterization using the novel versatiletransducer, thereby enabling medical specialists to conveniently applyhigh resolution B-scan image information as a guiding image to use withtwo-frequency A-mode tissue characterization for accurate determinationof tissue types when performing ultrasound imaging procedures. Thissystem would employ a switching mechanism to switch the system betweenB-scan mode and tissue-characterization mode.

It is a further object of the present invention to improve the qualityof ultrasound diagnostic examination with a system having a novelversatile combination transducer in which the transducer is fabricatedfrom an existing B-scan transducer currently available on the market orfabricated de novo. The system is configured to be switched by anoperator between B-mode imaging and A-mode tissue characterization. Thecombination transducer uses a conventional piezo-element array as aB-scan transducer and includes a separate piezo-element, which functionsas an A-mode transducer, that is dedicated for two-frequency A-modeoperation for tissue characterization. The combination transducer mayhave the A-mode piezo-element installed in a common housing with aB-scan piezo-element array or it may be contained within its own housingthat is externally attached to the housing of a B-scan transducer.Alternatively, the B-mode transducer and A-mode transducer do not needto be physically attached to each other.

In accordance with one embodiment an operator uses the system byapplying a YB-scan transducer receiving two-frequency excitation pulsesfor simultaneous generation of YB-scan tissue images and generation oftwo-frequency tissue characterization data and images. An operatorplaces the YB-scan transducer on a patient's body; displaying YB-scantissue images on a monitor; analyzes the YB-scan tissue images; selectsa region of interest on said displayed YB-scan images on said monitor;displays A-mode signals on the screen next to the displayed said YB-scanimages on said monitor; then the operator obtains objective attenuationdata to determine the tissue type by automatically by having the systemprocess the attenuation data or by visually analyzing he A-mode signalsfrom the chosen region. The tissue characterization data may bedisplayed on the monitor next to the YB-scan image.

The embodiments using conventional B-mode scanning in combination withtwo-frequency A-mode tissue characterization require switching of thesystem between A-mode and B-mode operation. These embodiments involveperforming B-scan imaging, selecting a region of interest followed byA-mode scanning of the spot of interest with two-frequency attenuationanalysis for tissue characterization.

Details of the apparatus of present invention are set forth in thefollowing detailed description and the accompanying drawings whereinlike reference numerals depict like elements.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic representation of an apparatus which can performsimultaneous application of the YB scan imaging and the tissuecharacterization method.

FIG. 2 is a schematic representation of a second embodiment which uses aswitching mechanism to switch an ultrasound imaging system betweenconventional B-mode scanning and a two-frequency tissue characterizationmode.

FIG. 3 is a schematic representation of a switching mechanism whichenables an ultrasound imaging system according to the principles of theinvention to switchably operate in either a two-frequency A-scan mode ora conventional B-scan mode.

FIG. 4 schematically illustrates a system according to some embodimentsof the invention wherein an adapter facilitates connections between aB-mode apparatus, a two-frequency apparatus, and a combined A-scan andB-scan transducer.

FIG. 5 is a schematic representation of a third embodiment of theinvention which uses a switching mechanism to switch an ultrasoundimaging system between conventional B-mode scanning and a two-frequencytissue characterization mode.

FIG. 6 is a schematic representation of a fourth embodiment of theinvention which uses a switching mechanism to switch an ultrasoundimaging system between conventional B-mode scanning and a two-frequencytissue characterization mode.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIG. 1 illustrates an apparatus that isconfigured to function by simultaneously to producing 2-dimentionalimages (hereafter ‘YB-scan images’), which are analogous to B-scanimages, and also producing two-frequency characterization data. It mayalso produce a visual representation of the two-frequencycharacterization data. The apparatus 10 of FIG. 1 includes a pluralityof piezo-elements which function as a multi-element transducer 13(hereafter referred to as a ‘YB-scan transducer’). In a preferredembodiment, all the piezo-elements may function separately andindependently as an A-mode transducer. An arbitrary waveform generator11 can generate pulses as desired at two different frequencies withdesired width and shape. The apparatus 10 further includes a linear ina-sequence scanning system 12. The apparatus further includes a computersystem 16 or controller. The computer system or controller further hasmemory 18 for storing reflected signals data, display memory 19, atwo-frequency A-mode analyzer 20 and a monitor 15. The apparatus mayalso include a voice recognition device 17.

The excitation pulses from a waveform generator comprised of severalsine-waves for each chosen frequency of two different frequencies areapplied in sequence and the pulses separately excite each of theindependently functioning piezo-elements of the YB-scan transducer. Byconnecting independently functioning piezo elements of a YB-scantransducer to a linear in-sequence scanning system a YB-scan image of atissue is created with simultaneous application of A-mode signalsthereby permitting calculation of attenuation data.

Each piezo- element of said YB-scan transducer 13 emits and receivessignals on two different chosen frequencies having a specified width andshape from the waveform generator 11. An operator can place the multipiezo-elements YB-scan transducer 13 on the surface of the body of apatient 14 and display in a sequence two YB-scan images on two differentfrequencies for visualization on a monitor 15 by using computer system16 with a program memory and control systems that are available on themarket having all the features necessary for examination and analyzes ofthe YB-scan images so that the YB-scan images can be displayed in asequence or individually by choice. On the screen of monitor 15 anoperator can analyze any spot of interest on the YB-scan images byapplying the tissue characterization method to determine the attenuationdata for the spot of interest in the tissue under examination. Analysisof the A-mode signals from the chosen spot and calculation of theattenuation data from the chosen spot can be processed automatically anddisplayed as an overlay on the chosen spot on the screen displaying theYB-scan images. A living body consists of different types of tissueshaving layers and boundaries. A YB-scan imaging method displays thestructure of the tissue layers and their boundaries. In many cases thisinformation is not enough to differentiate the type of tissue. Thetissue characterization apparatus can differentiate the type of tissuebut only through reflected signals from boundaries of the layers becauseexisting technology does not have enough accuracy to measure attenuationin the tiny structures of the tissue. The tissue characterization methodrequires two reflected signals to calculate the attenuation data betweenthe reflected signals: one reflected signal from front boundary of thelayer and a second reflected signal from the rear boundary of the layer.The YB-scan transducer 13 as described above consists of multiplepiezo-elements which function independently for YB-scan imaging and forsimultaneous tissue characterization according to the two-frequencymethod. The operator must know that each piezo-element has its ownreflected image display. To measure attenuation in a spot of interestfound through YB-scan image requires finding two reflected signalscoming from the same piezo- element. The operator must click on a chosenreflected signal on the YB-scan image and a line will appear to show thedirection of the reflected signals coming from the piezo- element. Theoperator must find and click on the second reflected signal from thesame piezo-element and it should be a rear boundary of the chosen layer.The attenuation data will be displayed by choice on the YB-scan imagescreen as an overlaid color image or as numerical data between thechosen reflected signals or displayed as numerical data on a smallerscreen next to the YB-scan image display on the monitor 15. If neededthe operator can see and analyze the reflected signals from thecorresponding piezo-element as A-mode signals which can be displayed onthe screen of the monitor 15 next to the YB-scan image display. On thetop of the YB-scan imaging screen of the monitor 15 there are numberscorresponding to each piezo-element of the YB-scan transducer 13. Byclicking the number an operator can activate the direction line of thepiezo-element. The operator also can use a Voice Recognition block 17 toactivate the direction line of any piezo-element by pronouncing a numberto find a corresponding piezo-element. The operator also can use A-modeAnalyzer block 20 to make analyses of said A-mode signals automatically.The display of YB-scan tissue images simultaneously with overlaid tissuecharacterization information will greatly improve the quality ofultrasound diagnostic examinations.

In accordance with the present invention the combined method of B-scanimaging with the two-frequency tissue characterization can also beaccomplished by using a high-resolution B-scan system having a B-scantransducer with an array of piezo-elements.

The embodiment of FIG. 2 has a combined transducer which can receive twodifferent types of excitation pulses for performing high-resolutionB-scan imaging and two-frequency attenuation analysis for tissuecharacterization. The two-frequency attenuation method requires oneemitting and receiving source of ultrasound signals. An operatorperforming the tissue characterization method determines the tissue typefrom analysis of the registered reflected signals from the tissue. Formedical specialists it is very important to know from what part of theregion of interest the attenuation data is coming from. The same problemwas encountered with needle biopsy examination procedures. Laterspecialists invented x-ray and ultrasound guiding images for needlebiopsy procedures. The same problem exists with applying tissuecharacterization examination. It needs two-dimensional image informationto direct an A-mode transducer to a chosen spot in a region of interest.A B-scan transducer has a plurality of tiny piezo-elements and requiresvery short excitation pulses. A-mode transducers require sinusoidalexcitation pulses using two different frequencies. The A-mode transducermust be much larger than a single conventional B-mode piezo-element toemit a signal with sufficient strength to generate reflected signalssuitable for two-frequency attenuation analysis. The A-mode transducerrequires independent functioning piezo-elements in both emitting andreceiving modes but the B-scan transducer's piezo-elements are notindependent functioning. For these reasons an A-mode transducer can beintegrated with a B-scan transducer by redesigning the function of somepart of its piezo-elements to connect them together through a switchingsystem to function as A-mode transducer and to connect with the waveformgenerator of tissue characterization apparatus for sinusoidal excitationpulses on two different frequencies. The designed A-mode transducerbecomes independent functioning for the period of tissuecharacterization examination. The middle part of B-scan transducer isthe best place to design A-mode transducer. The A-mode transducer may becomprised of a row of the piezo-elements. The required number of tinypiezo-elements that should be connected together to make an A-modetransducer will depend on the applied frequencies used and the depth ofregion of interest. Electronic switch mechanism should considerdifferent options of number of the tiny piezo-elements to be connectedtogether to function as an A-mode transducer for the operator to apply.There is another switching function in this embodiment which should turnON the functioning apparatus and turn OFF another one with switching ata controllable speed because the best of examination can be when theoperator visualizes both images on the screen of monitor almostsimultaneously. This embodiment has a combined transducer that uses anA-mode transducer inside of a B-scan transducer. The combined transducercan be fabricated from a pre-existing conventional multi-piezo-elementB-scan transducer. The A-mode transducer is comprised of a subset orgroup of piezo-elements of the pre-existing B-scan transducer.

A B-scan transducer is positioned in a housing 7, the B-scan transduceris comprised of a plurality of piezo-elements 8 in an array. A switchingmechanism 1 is configured to reversibly connect a group of adjacentpiezo-elements 5 from the plurality of piezo-elements such that thegroup of piezo-elements together function as an A-mode transducer 6. Afoot pedal switch 9 is used by an operator to reversibly activateswitching mechanism 1 to actuate A-mode transducer function. When A-modefunction is actuated the switching mechanism electronically communicateswith both the two-frequency apparatus and the group of piezo-elementsfunctioning in A-mode within the transducer housing. When A-modefunction is not activated, the switching mechanism electronicallycommunicates with the B-mode apparatus 2. It is evident to a person ofordinary skill in the art that the arrangement of the group of adjacentpiezo-elements 5 can be a row of piezo elements or another suitableconfiguration.

The foot pedal effectively toggles the system between said B-scan modeand two-frequency tissue characterization A-scan mode thereby enablingboth B-scan imaging and tissue characterization imaging.

By using a B-scan image as a guiding image, an operator can select aregion of interest to be scanned in two-frequency A-mode for tissuecharacterization thereby improving the quality of existing ultrasounddiagnostic examination methods.

In accordance with the present invention any currently marketed B-scanapparatus with B-scan transducer having a plurality of piezo-elementscan be adapted for combining conventional B-scan examination andtwo-frequency tissue characterization essentially by employing aswitching mechanism such as shown in FIG. 3. The switching mechanism canbe integrated into the system through an interface adapter as shown inFIG. 4, thereby allowing the system to function for B-scan imaging andtwo-frequency tissue characterization imaging. By combining B-scanimaging and two-frequency tissue characterization improved quality ofexisting ultrasound diagnostic examination can be achieved.

FIG. 3 is a block diagram of an electronic switching mechanism which canconnect together some of the piezo-elements of a B-scan transducer tomake a connected adjacent group of piezo-elements to function as anA-mode transducer as describe above (see FIG. 2) for two-frequencytissue characterization.

Electronic switching mechanism (FIG. 3) works through a TTL logic levelsignal via Analog Switch 1. When it is driven with a logic “1” theSystem 2 of the ultrasound apparatus is connected to the transducer Head3. Also, it is “pulled up”, when nothing is connected to the input, theultrasound apparatus System 2 is connected to the transducer Head 3.When it is driven with a logic “0” (or shorted to ground) all elementsare disconnected from the ultrasound apparatus System 2 and the “IN”signal from tissue characterization apparatus 4 through B-port of saidAnalog Switch 1 is connected to the central elements of the transducerHead 3. A high voltage switch IC can be used for a relay which providesswitching of the group of piezo-elements 5 between the B-scan apparatus2 and the Tissue Characterization apparatus 4. The remaining number ofpiezo-elements have a single switch for each piezo-element so that allpiezo-elements of the B-scan transducer see the same impedance whendriven by the B-scan apparatus. These switches are opened bydisconnecting the B-scan apparatus's system from the transducer when theexternal transceiver is connected to the group of piezo-elements 5.

The electronic switching mechanism of FIGS. 2 & 3 can be installedwithin the interface adapter shown schematically in FIG. 4. Theinterface adapter is constructed with a space 42 to accommodate theswitching mechanism. The interface adapter connects the B-scantransducer 7 (FIG. 2) with the B-scan apparatus 2 through the switchingmechanism described above.

An interface adapter housing 30 holds two types of connectors. Aconnector 36 on the front side of the interface adapter is configured toconnect with the B-scan apparatus at connector 34. Another connector 38on the lateral side of interface adapter allows for connection of theB-scan transducer to the interface adapter by connecting connector 40with connector 38. The interface adapter is also connected to thetwo-frequency apparatus. The interface adapter can be locked or unlockedusing a rod with handle 32.

In another aspect of the present invention existing ultrasounddiagnostic examination can be improved by combined application of aB-scan imaging method and A-mode two-frequency tissue characterizationwith a conventional multi piezo-element B-scan transducer having asingle piezo-element inserted within the housing of the B-scantransducer. Unlike the embodiment of FIG. 2, which utilizes a subset orgroup conventional tiny B-mode piezo-elements to reversibly form anA-mode transducer, the embodiments of FIGS. 5 and 6 utilize a singlelarge A-mode piezo-element as the A-mode transducer.

FIG. 5 is a schematic illustration of a combined transducer whichintegrates a B-scan transducer having an array of piezo-elements 8 withan inserted A-mode transducer 6 within housing 7. The B-scan transduceris comprised of plurality tiny piezo-elements for B-mode scanning andthe A-mode transducer 6 is comprised of a single piezo-element 5—whichis larger than the tiny B-mode piezo-elements. The A-mode transducer isconnected directly to the tissue characterization apparatus 4. TheA-mode transducer 6 functions separately and independently from thepiezo-element array 8 of the B-scan transducer. The size of the A-modetransducer piezo-element depends on the values of the applied twofrequencies and the depth of a region of interest to be characterized inthe patient's body and also depends on the particular organ underinvestigation. The combined examination starts with B-scan visualizationprocess whereby an operator finds a spot or region of interest. Theoperator then depresses a foot pedal or other convenient mechanicalmeans to switch from B-mode to A-mode scanning and slides the combinedtransducer to position the A-mode transducer for examining the spot orregion of interest. An advantage of this embodiment in comparison to theembodiment of FIG. 2 is that the switching mechanism does not need to beconnected directly to the piezo-elements of the combined transducer.This is because the dedicated A-mode piezo-element does not need to beelectronically connected to a group dual-function piezo-elements. Thesingle piezo-element transducer can also function as a focusedtransducer when needed.

Reflected signals are analyzed by shape, width and registered timevisually or automatically through two-frequency analyzer block to obtainattenuation data for the chosen spot of interest thereby permittingdetermination of the type of tissue under investigation.

Another embodiment using a single A-mode piezo-element for tissuecharacterization in combination with a B-mode transducer is shown inFIG. 6. Any commercially available B-scan apparatus with any type ofB-scan transducer can be adapted for combined B-scan imaging and A-modetwo-frequency tissue characterization according to this embodiment whichis similar to the embodiment of FIG. 5, having an A-mode transducer 6comprised of a single piezo-element 5, but the single A-modepiezo-element in the embodiment of FIG. 6 is positioned within its ownhousing 27 which is in turn affixed to the B-mode transducer housing 26.This embodiment is essentially the same as the embodiment of FIG. 5except that the A-mode transducer is external to the B-scan transducerhousing.

During the examination of the patients by placing the bodies of saidB-scan transducer and said A-mode transducer adjacent to each other asone combined transducer and to use B-scan visualization as a guidingimage information to apply tissue characterization method. Theexamination process of the patients is the same as practiced for theembodiment of FIG. 5. Any existing B-scan apparatus on the market can beconfigured with adjacent B-scan and A-mode transducers according to thisembodiment.

It is apparent that there has been provided in accordance with thisinvention devices and methods for non-invasively determining a type oftissue within a living entity which fully satisfies the objects, meansand advantages set forth herein. While the invention has been describedin combination with specific embodiments thereof, it is evident thatmany alternatives, modifications and variations will be apparent tothose skilled in the art in light of the foregoing description.Accordingly, it intended to embrace all such alternatives, modificationsand variations as fall within the spirit and broad scope of the appendedclaims

I claim:
 1. An ultrasound imaging system to be used by an operatorcomprising: a YB scan transducer (13) having a plurality of piezoelements wherein each of the piezo elements are configured to functionseparately and independently as A-mode transducers, said piezo-elementsconfigured to be excited in sequence at two different frequencies,wherein said two different frequencies are applied in sinusoidaltwo-pulse sequences, said piezo-elements further configured to receivereflected signals at said two different frequencies which are applied insaid two-pulse sequences, a waveform generator, said waveform generatorconfigured to produce the two sinusoidal impulses on two differentfrequencies in said two-pulse sequences, a scanner system, a computersystem or controller, said computer system or controller having memoryfor storing reflected signals data and memory for display, atwo-frequency A-mode analyzer, a monitor, a linear in-sequence scanningsystem, said transducer connected to said linear in-sequence scanningsystem, said waveform generator in electronic communication with saidscanner system and said computer system or controller, said scannersystem also in electronic communication with said computer system orcontroller, said system further configured to generate at least onetwo-dimensional YB-scan images corresponding to said two differentfrequencies applied in sequence, said system further configured whereinsaid two-frequency A-mode analyzer receives reflected signal data fromtissue layers and further wherein said two-frequency A-mode analyzerfinds or permits the operator to find a pair or pairs of reflectedsignals of said two different frequencies, said pair of reflectedsignals deriving from the same single piezo-element or said pairs ofreflected signals each deriving from a respective single piezo element,said two-frequency A-mode analyzer configured to analyze said reflectedsignals on said two different frequencies to determine frequency, shape,width and registered time of said reflected signals, and sends selectedreflected signals on said two different frequencies to the computer tocalculate a differential attenuation coefficient for the tissues underinvestigation, thereby generating two-frequency attenuation information,said system further configured to display said at least onetwo-dimensional YB-scan image from wherein said YB-scan image may becombined with said two-frequency attenuation information in an enhancedimage or be displayed separately as required by the operator, therebypermitting differentiation between types of tissue within an organ. 2.The ultrasound imaging system of claim 1 further comprising, whereinsaid plurality of piezo elements is comprised of a row ofpiezo-elements.
 3. The ultrasound imaging system of claim 1 furthercomprising, wherein said waveform generator is configured to produce twotypes of excitation pulses in a sequence or alternating, said two typescomprising said two sinusoidal pulses in said two-pulse sequence, saidtwo-pulse sequence comprising pulses of two different frequencies, and asecond type or pulses having greater amplitude and shorter duration thansaid two sinusoidal pulses in said two-pulse sequence.
 4. The ultrasoundimaging system of claim 1 further comprising wherein said imaging systemis configured to display said two-frequency A-mode information as atwo-frequency attenuation image.
 5. The ultrasound imaging system ofclaim 3 further comprising wherein said imaging system is configured todisplay said two-frequency A-mode information as a two-frequencyattenuation image.
 6. A method for non-invasively determining at leastone of a type of a tissue matter and a state of said tissue matter in aliving body using an apparatus, said method comprising the steps of:providing said apparatus having a YB scan transducer (13), said YB scantransducer comprising a plurality of separately and independentlyfunctioning piezo-elements, said transducer configured to be placed onsaid tissue matter, said apparatus further having a waveform generatorfor generating sinusoidal pulses at two different frequencies, saidapparatus yet further having a linear in-sequence scanning system,reflected signal memory, and a two-frequency analyzer, said waveformgenerator generating said pulses at said two different frequencies,supplying said pulses at said two different frequencies to saidtransducer, directing said pulses at said two different frequencies to atissue, receiving reflected signals data, storing reflected signal dataat said two different frequencies in said reflected signal memory,storing digital two-dimensional image data in display memory, generatingtwo-dimensional YB-scan images at said two different frequencies,displaying at least one two-dimensional YB-scan image on a monitor,choosing a spot in a region of interest on said at least onetwo-dimensional YB-scan image, determining received reflected signalsregistered from a same piezo-element, displaying A-mode images on saidmonitor, said A-mode images generated from said reflected signal data onsaid two different frequencies, wherein said A-mode images are displayedalong with said at least one two-dimensional image, analyzing A-modereflected signals from the spot in said region of interest to determinefrequency, shape, width and registered time of said A-mode reflectedsignals, creating a two-frequency attenuation image of said spot in saidregion of interest on said monitor, determining a type of tissue matterand the state of the tissue matter.